This is what Titanfall looked like using the Ratchet & Clank engine

In Geoff Keighley's newly released The Final Hours of Titanfall documentary, it was revealed that Insomniac Games founder Ted Price offered Respawn Entertainment co-founde rVince Zampella free use of Insomniac's "Luna" engine to make Titanfall. Taking him up on the offer, Respawn actually prototyped Titanfall -- then known as "R1" -- for about one year using this same technology that powered Ratchet & Clank: A Crack in Time. And here's a screenshot of what Titanfall looked like.

As you can see, it's quite different from the game we all know today as Respawn eventually built their own engine for the game, but it's certainly an interesting comparison.

Also revealed in the documentary was that Respawn actually approached Sony about bringing their game to PS4, but Sony wasn't yet ready to talk specs. Instead, they offered to help Respawn make a Vita version. It's crazy what goes on behind the scenes.